Ultrahigh-frequency aerials



April 9, 1968 J. ROBIEUX ETAL 3,377,592

ULTRAHIGH-FREQUENCY AERIALS Filed Nov. 24, 1959 5 sheets-shed 1INVENTORS JEA N ROB/E UX ROGER DUMANCH/N April 9, 1968 J. ROBIEUX Em.3,377,592

ULTRAHIGH-FREQUENCY AERIALS IN VENTORS JEAN ROB/E UX ROGER DUMA NCH/NApril 9., 1968 J. ROBIEUX ETAL 3,377,592

ULTRAHIGH-FREQUENCY AERIALS Filed Nov. 24, 1959 5 SheetS-Sheet b PHASEDISCRIMINATOFL .SOURCE INVENTORS JEAN ROB/EUX ROGER DUMANCH/N 3,377,592ULTRAHlGH-FREQUENCY AERIALS Jean Robieux and Roger Dumanchin, Paris,France, as-

signors to Compagnie Generale de Telegraphie Sans Fil, a corporation ofFrance Filed Nov. 24, 1959, Ser. No. 855,233 Claims priority,application France, Dec. 5, 1958, 780,930 4 Claims. (Cl. 343-100) Thepresent invention relates to ultarhigh-frequency directional aerials.More particularly, it relates to electrically controlled aerials, i.e.to aerials of the type wherein the scanning of the space is obtainedelectrically without actual rotation of the aerial.

It is an object of the invention to provide an improved aerial of thistype and it is a Ifurther object of the invention to provide an aerialof this type which is particularly adapted for being supported on a flatsurface in such a way that any interference with the aerodynamicalcharacteristics` of a ilying body provided with this aerial is avoided.

An aerial according to the invention comprises an assembly of paralleltransmission lines having equidistant radiating discontinuities, a waveguide for feeding energy to the aerial, a ferrite rod extending axiallyof the guide and a coil structure surrounding the guide for providingtherein a magnetizing tield directed along the axis of said ferrite rod.

The transmission lines may be microstrip lines, the radiatingdiscontinuities being built up by line lengths where at least one edgeof the line is shifted laterally with respect to the general direcitonof the line, as more particularly disclosed in the copending PatentApplication Ser. No. 855,234, filed Nov. 24, 1959.

According to a particular embodiment of the invention, cach radiatingdiscontinuity is shifted lengthwise of the line with respect to thecorresponding discontinuity of the adjacent line, in such a manner thatthe phase velocity of the wave in the guide is higher than the velocityof light.

The invention will be best understood from the following description andappended drawing wherein:

FIG. l is a perspective view of an aerial according to the invention;

FIG. 2 is a cross sectional view of the aerial of FIG. 1;

FIG. 3 is a partial top View of the aerial of FIG. l;

F IG. 4 is an explanatory diagram;

FIG. 5 is a variation of FIG. 3;

FIG. 6 is an explanatory diagram;

FIG. 7 shows an aerial according 4to the invention, mounted on the wingsof a high speed flying body;

FIG. 8 is a block-diagram of a control device;

FIG. 9 illusrtates, very diagrammatically and in crosssection, a furtheraerial according to the invention.

The radiating device shown in FIG. 1 comprises a rectangular Wave-guide1 along the axis of which extends a ferrite rod 2. Coils 3 are woundaround Wave-guide 1 and generate therein a magnetic field H directedalong the axis thereof. l

A plurality of microstrip lines having a common ground plate 5, a commondielectric plate 8 and strips 6 extend in perpendicular relationship tothe axis of guide 1. They are coupled to guide 1 by means of probes 4and are spaced apart by M2, where )t is the length in free space of theoperating wave.

Strips 6, which are otherwise of a known type, comprise radiatingdiscontinuities 7. These ydiscontinuities are spaced apart by as, )tsbeing the wave length in the line of the operating wave and are obtainedby laterally shifting portions of at least one of the edges of the line.

United States Patent O Patented Apr. 9, 1968 f. ICC

FIG. 2 shows a cross-sectional view of the assembly shown in FIG. 1.Ground plate 5 is supported on a block 9 which rests on one of the largesides of guide 1. Each block 9 comprises a hole 10 which is lined withthe dielectric material forming plate 5. This material builds up theouter conductor of a co-axial cable. Probe 4, which extends into guide1, forms the inner conductor of this coaxial cable.

FIG. 3 shows the strips as seen from above. Four strips 61, 62, `63 and64 are shown. Discontinuities 7 build up rows spaced apart by M2 andcolumns spaced apart by ks, as mentioned above.

The radiating assembly of FIG. l operates as follows:

Considering first only the rows it is apparent that all thediscontinuities 7 of a line are fed in phase. Consequently, the assemblyradiates in the mean plane of the large sides of guide 1.

If, now, the columns built up the radiating elements 7 respectivelypertaining to lines 61, 62, 63 and 64 are considered, they radiate in aplane making with the plane comprising strips 6 an angle 0 delined bythe well known equation cos M Thus, the radiation direction is define-dby the intersection of the two planes mentionied above, this directionbeing inclined to the plane containing strips 6 and making therewithangle 0.

According to the invention, this angle can be modified.

It is known that a ferrite piece placed in a guide and subjected to alongitudinal magnetic field modifies the phase velocity of the wavepropagating therein. This phase velocity varies as a function of themagnetic field, the corresponding curve having the shape of a hysteresisloop, as shown in FIG. 4 where Vg is the phase velocity of the Wave inguide 1 and I the intensity of the current owing in coils 3.

If the phase velocity is higher than the velocity of light, i.e. if xgis greater than c, the aerial has a .maximum directivity along adirection forming an angle 92 with the axis of guide 1, with If,however, the presence of ferrite 2 in guide 1 delays the wavepropagation suiciently Afor Vg to become smaller than c, this is nolonger true, since c/Vg is greater than 1.

In this case, particularly in order to make the radiation possible inspite of the presence of the ferrite in guide 1, the apparent or phasevelocity of the wave propagating in the guide in the direction of theaxis of the guide must be rendered artificially greater than thevelocity of light.

VReference is made in this respect to FIG. 6 where the variations ofphase of the wave propagating in guide 1 are plotted along the axis ofordinates against distances taken along the axis of the guide taken asabscissae.

The propagating wave being expresse-d by Z Z e (w g 7D- -I-gAccordingly, go=f(Z) is a straight line, the slope of which is inverselyproportional to Vg. l

In FIG. 6 curve 1 corresponds to Vg=c, curve 2 to Vg c and curve 3 to Vgc.

As may be seen from FIG. 6, in order to pass from a point on curve 2 tothe point of the same abscissa on curve 3, it suliices that, at thepoint of guide 1 having this abscissa, the wave is delayed by p=KZ, Kbeing a constant. Such a phase-shift may be obtained by a suitablearrangement of the elementary radiating sources, i.e. of discontinuities7.

This is achieved in the arrangement of FIG. 5. The respectivediscontinuities 7 of lines 61 and 64 no longer built up columns, but arelaterally shifted with respect to each other by the same distance toform a staggered arrangement.

FIG. 7 shows a missile 100 having wings 101 to which an aerial 102according to the invention is applied. Arrows indicate directions ofradiation. They make with wings 101 an angle 0 which can be modified bymodifying the magnetic iield to which the ferrite element is submitted.The printed-circuit techniques allow of a great precision in themanufacturing of aerial structures according to the invention even inthe millimeter band.

High directivity aerials may thus be readily provided. For 1 mm.wavelength, a pencil-beam of a beam angle of 1/1000 radians may bereadily obtained with an aerial extending over 1 metre.

An aerial according to the invention which is capable of scanning spacewithout actual rotation of any mechanical element is susceptible of manyapplications. Wide angular sectors may thus be scanned in very shortperiods of times: for example, a sector of 45 may be scanned in 1 mms.

FIG. 4 shows that phase velocity Vg is not a univocal function of themagnetizing eurent I. Accordingly, if I is known, angle is notnecessarily known. As shown in FIG. 8, a phasemeter 200 `can be used fordetermining 0. Since c i/fi.

0 is known if Vg is known.

Phasemeter 200 measures the phase `diilerence of the wave between thepoints A and B in the mean plane of guide. Accordingly it measures thephase velocity Vg.

In order to reduce insertion losses, due to the insertion of the ferriteelements into the guide, and the secondary lobes, the aerial assemblymay be built up as shown in FIG. 9. It comprises two aerial structuressimilar to those described so far and respectively comprising guides 101and 102 placed end-to-end. Guides 101 and 102 comprise respectiveferrite rods 201 and 202 as explained above.

Coils 301 and 302 surround guides 101 and 102 respectively. Guides 101and 102 respectively support ground plates S01 and 502 and the stripsare coupled to the guides by means of probes 401 and 402. A guide 103feeds energy to guides 101 and 102, the energy flowing in oppositedirections in the two guides. Two probes are located at points A and B,symmetrically with respect to the axis of guide 101.

A phase discriminator 104 provides a control voltage which is a functionof the phase difference at A and B. This control voltage controls in anysuitable manner the energy fed from a source 105 to coils 401 and 402 insuch a manner that pA= pB- Referring now to FIG. 6, it is readily seenthat if curve 2 corresponds, as explained above, to the function p=f(Z),for example in guide 101, curve 4 making with the axis of abscissae thesame angle as curve 2 corresponds to p=f(Z) in guide 102. Under theseconditions if, as also explained above, g0=f(Z) is shifted from curve 1to curve 3 by suitably shifting the radiating sources with respect toeach other, it will suflice to shift suitably with respect to each otherthe radiating sources fed from guide 102 in order to have along guide102 a phase propagation corresponding to to the angle 0, if this angleis 0 in the case of the aerial portion fed from guide 101. Thus itappears that both aerial sections 101 and 102 will radiate in the samedirection.

Of course the invention is not limited to the embodiments shown anddescribed which were given solely by way of example.

What is claimed is:

1. An ultrahigh-frequency directional aerial, comprising in combination:a waveguid e for propagating ultrahigh-frequency energy; at least oneset of parallel identical microstrip lines, extending in a directionperpendicular to said wave guide and spaced apart by one half of thewave length in fre space of said energy; means for coupling said stripsto said guide; said microstrip lines having radiating discontinuitiesspaced apart in each line by a wave length of said energy in said lines,said discontinuities forming in each of said sets rows inclined over thesymmetry plane of said guide; at least one ferrite rod extending alongsaid wave guide; and coils surrounding said rod for controlling thephase velocity of the ener-gy in said wave guide.

2. An ultrahigh-frequency directional aerial comprising in combination:two wave guides having a common input for propagatingultrahigh-frequency energy in opposite directions; two sets of parallelidentical microstrip lines, extending in a direction perpendicular tosaid wave guides, the distance between two consecutive strip lines in aset being equal to one half of the wave length of said energy in freespace; means for coupling said strips to said guides; said vmicrostriplines having radiating discontinuities, spaced along each line by awavelength of the energy propagating therein, the discontinuities havingthe same relative position in each line being arranged in rows inclinedover said guides; two respective ferrite rods extending in said waveguides; and respective coils surrounding said two rods for controllingthe phase velocity ofthe energy in said wave guides.

3. An ultrahigh-frequency directional aerial comprising in combination:two wave guides having a common input for propagating ultra highfrequency energy in opposite directions; two sets of parallel identicalmicrostrip lines, extending in a direction perpendicular to said waveguides; the distance between two consecutive strip lines in a set beingequal to one half of the wave length of said energy in free space meansfor coupling said strips to said guides; said microstrip lines havingradiating discontinuities spaced along each line by a wavelength of theenergy propagating therein, the discontinuities having the same relativeposition in each line being arranged in rows inclined over said guides;two respective ferrite rods extending in said wave guide; respectivecurrent conductive coils surrounding said rods for controlling the phasevelocity of the energy in said wave guide; a phase discriminator coupledto said wave guides; and means controlled by said discriminator forcontrolling the current ow in said coils.

4. An ultrahigh-frequency directional aerial comprising in combination:a first transmission line for propagating wave energy: electrical meansfor controlling the phase velocity of said energy along said line; aplurality of parallel and equally spaced second trans-mission lines,coupled to said rst transmission line, said second transmission lineshaving radiating elements equally spaced from each other in each line,the radiating elements of said lines building up rows inclined over saidrst transmission line.

References Cited UNITED STATES PATENTS OTHER REFERENCES Proceedings ofthe I.R.E., November 1957, pp. 1510- RODNEY D. BENNETT, PrimaryExaminer.

`CHESTER L. JUSTUS, Examiner.

R. E. BERGER, Assistant Examiner.

4. AN ULTRAHIGH-FREQUENCY DIRECTIONAL AERIAL COMPRISING IN COMBINATION:A FIRST TRANSMISSION LINE FOR PROPAGATING WAVE ENERGY: ELECTRICAL MEANSFOR CONTROLLING THE PHASE VELOCITY OF SAID ENERGY ALONG SAID LINE; APLURALITY OF PARALLEL AND EQUALLY SPACED SECOND TRANSMISSION LINES,COUPLED TO SAID FIRST TRANSMISSION LINE, SAID SECOND TRANSMISSION LINESHAVING RADIATING ELEMENTS EQUALLY SPACED FROM EACH OTHER IN EACH LINE,THE RADIATING ELEMENTS OF SAID LINES BUILDING UP ROWS INCLINED OVER SAIDFIRST TRANSMISSION LINE.